1. Technical Field
The present invention relates to an improvement of a bearing portion of the motor of the hard disk drive device.
2. Description of the Prior Art
The hard disk drive device employs in general a motor such as a spindle motor for rotating magnetic disk means for storing data. The motor includes a shaft, a rotor, base, and stator. The rotor as rotating member is adapted to be journalled to extend vertically to the base by means of bearing means installed on the base.
The bearing apparatus of the prior art as shown in FIG. 4 comprises a pair of ball bearings 21, 22 fitted on a shaft 23. The bearings 21, 22 are spaced apart for example by means of spacer 24 secured on the shaft 23.
The major problem of the hard disk drive device is to reduce the size thereof. That is, it is desirable to make the rotor of the motor and the bearing means for supporting the rotor as small as possible.
The way which can be adapted to reduce the size of the bearing means is to miniaturize both ball bearings of the pair. However, this countermeasure leads to the reduction of the diameter of the shaft.
The shaft of reduced diameter provides a problem of reduced mechanical rigidity to impair the reliability and vibration-proof property of the hard disk drive device. Further, the shaft of reduced diameter becomes resonant with members of the hard disk drive device surrounding therearound e.g. the casing of the device. That is, the reduction of the resonance property will be accompanied by the reduction of the reliability of the hard disk drive device.
The object of the present invention is to provide a hard disk drive device including a compact enough double row bearing apparatus having a shaft of sufficient mechanical rigidity.